On Tue, Nov 12, 2002 at 04:15:25PM -0000, Chris Gilbert wrote:
> An optimisation I've just thought of, is it worth adding flags to the
> pvh_attrs field of the vm_page_md stuff that indicates that all entries in
> this vm_page list are readonly and therefore all cacheable? that way when
> we add a new readonly pv to the list we don't have to walk the list, we
> just add it in.
I'd use counters -- a flag might require a traversal of the list again
to update the flag. A counter would not.
Maybe use:
- kernel-writable
- user-writable
- read-only
as the counters? This way you only need to incr/decr the counters, and
check them for != 0. Counters should be unsigned, and sprinkle some
KDASSERT()s in there to detect underflow.
--
-- Jason R. Thorpe <thorpej@wasabisystems.com>